Mars rover targets a rock called Jake

The first rock that NASA's Curiosity rover will touch for science's sake on Mars is a pyramid-shaped chunk that's been named in honor of a top engineer who worked on every one of NASA's rover missions — but passed away just days after Curiosity's landing.

Curiosity's study of the rock, dubbed "Jake Matijevic," will dominate the next few days of the rover's operations on Mars, just as its observations of Martian mini-eclipses dominated the past few days.

Jake the rock, which measures about 10 inches (25 centimeters) tall and 16 inches (40 centimeters) wide, isn't all that exotic. It seems to consist of garden-variety basalt, similar to the first Martian rock that NASA's Spirit rover examined eight and a half years ago. And that's exactly the point, according to Caltech's John Grotzinger, project scientist for the Curiosity mission. Jake will provide a good yardstick for sophisticated instruments such as the Alpha Proton X-Ray Spectrometer, or APXS, and the laser-zapping ChemCam analyzer.

By matching up the chemical readings from the different instruments, Curiosity's science team will be able to confirm that the findings from the fancy-schmancy ChemCam are consistent with the readings from the APXS, an upgraded version of a device that was included on the Spirit and Opportunity rovers. Grotzinger told reporters today that it's an opportunity to compare "something which is tried and true with the latest and greatest new technology."

ChemCam can focus on areas that are less than a millimeter (0.04 inch) wide, while the APXS' best resolution ranges around 1.5 centimeters (0.6 inch).

Grotzinger estimated that the testing could begin on Friday — which is the Martian day, or sol, after tomorrow ("solorrow," he quipped). It could take a couple of sols for the rover to reach out its 7-foot-long (2.1-meter-long) robotic arm and use the APXS as well as the fine-resolution Mars Hand Lens Imager, or MAHLI. The rover might have to back up a bit to give the rock a proper zapping with ChemCam's laser. The flashes of light from the tiny laser blasts will be analyzed by an onboard spectrometer to determine the rock's elemental composition.

Remembering JakeRichard Cook, project manager for the $2.5 billion Mars Science Laboratory mission, said the rock's name pays tribute to Jacob Matijevic, a leading engineer at NASA's Jet Propulsion Laboratory who was involved in NASA's rover missions since Mars Pathfinder and the Sojourner rover in 1997. Matijevic was a Chicago native who earned his Ph.D. in mathematics and came up with the Matijevic Theorem, which was once described as "one of the most beautiful results of recent years in commutative algebra."

Matijevic's obituary in the Chicago Tribune notes that he came to JPL in 1981 and took on a variety of assignments. Eventually, he came to specialize in systems engineering for the Mars rover designs as well as rover surface operations. "He was probably one of the top one or two experts on surface operations here at JPL," Cook said.

Matijevic played a key role in the Spirit and Opportunity rover missions, which were originally planned to last just 90 days on Mars. Grotzinger recalled that Matijevic once said "if this rover lasts six months, it'll probably last six years."

"He seems to have come pretty close," Grotzinger observed.

The engineer switched over from Opportunity to the Mars Science Laboratory mission, but passed away at the age of 64 on Aug. 20, after battling respiratory problems, the Tribune reported.

Grotzinger said Matijevic would have loved dealing with the complexities involved in studying the rock that's named after him. "All that activity and all those considerations are what honor Jake Matijevic so well," he said.

The chief aim of Curiosity's two-year primary mission is to analyze Mars' geology and surface chemistry and determine whether the planet could have been potentially habitable in ancient times. After studying Jake's memorial rock, Curiosity is due to move on to an area known as Glenelg, where three types of geological formations come together.

Since its landing on Mars on Aug. 5, the six-wheeled rover has covered more than half of the quarter-mile (400-meter) distance to Glenelg, and its cameras are getting a better view of the place. Grotzinger said the pictures show thin bands of dark rock that appear to alternate with lighter-toned rock. "As we get closer in to the Glenelg area, we'll understand better and better what these areas are," Grotzinger said. Curiosity is expected to get to the area in a couple of weeks, he said.

NASA / JPL-Caltech / Univ. of Ariz.

This map shows the route driven by the Curiosity rover through the mission's 43rd Martian day, or sol (Sept. 19). By Sol 43, Curiosity had driven about 950 feet (290 meters). The area known as Glenelg is indicated by a red dot and label.

NASA / JPL-Caltech / MSSS

A scan of the Martian terrain looking toward Glenelg reveals areas of light and dark rock.

NASA / JPL-Caltech / MSSS

An animated GIF image shows Phobos crossing over the sun, as seen by NASA's Curiosity rover.

Messages from mini-eclipsesThe Curiosity team is also planning to receive more pictures of the partial solar eclipses that the rover's high-resolution Mastcam system has observed over the past week. Mark Lemmon, a science team co-investigator from Texas A&M University, said close analysis of the imagery could provide insights into the interior structure of Mars and its two moons, Phobos and Deimos.

Mastcam took hundreds of pictures when Phobos made two passes over the sun's disk, and again when Deimos made one pass. Such transits occur multiple times during a short season, and then they don't occur again for nearly one Earth year. Lemmon explained that the timing of the eclipses could be compared with past sightings to produce precise measurements of how the moons' orbits have changed due to Mars' gravitational tides.

"We can't go inside Mars, but we can use these to tell how much Mars is deformed when the moons go by," Lemmon said. "So we measure the transits very precisely [and] we get information on Mars' interior structure."

Phobos and Deimos have irregular shapes, and the prevailing wisdom is that they're both asteroids that were pulled into orbit by Mars' gravitational pull. Phobos averages 14 miles (22.2 kilometers) in width, and Deimos is roughly 8 miles (12.6 kilometers) wide. Deimos circles Mars at a distance of 14,580 miles (23,460 kilometers), while Phobos is much closer (5,800 miles, or 9,400 kilometers). Phobos is gradually coming even closer to Mars, which makes the moon's orbit unstable over the long term: One of these days, it will break up into pieces and perhaps produce a ring of debris around the Red Planet.

Fortunately, that day isn't expected to come for 10 million to 15 million years. "Curiosity will be safe for a little while," Lemmon said.